1. Pressure versus temperature ( P-T )
2. Pressure vs. volume ( P-v )
3. Temperature vs. volume ( T-v )
4. Temperature vs. information ( T-s )
5. Enthalpy vs. information ( h-s )
6. Pressure vs. heat content ( P-h )
The term impregnation temperature designates the temperature at which vaporisation takes topographic point.
For H2O at 99. 6 C the impregnation force per unit area is 0. 1 M Pa. and for H2O at 0. 1 Mpa. the impregnation temperature is 99. 6 C.
If a substance exists as liquid at the impregnation temperature and force per unit area it is called concentrated liquid.
If the temperature is of the liquid is lower than impregnation temperature at the bing force per unit area it is called sub-cooled liquid or compressed liquid.
1. When a substance exists as portion liquid and portion vapour at the impregnation temperature. its quality is defined as the ratio of the mass of vapour to the entire mass. 2. If a substance exists as vapour at the impregnation temperature. it is called a concentrated vapour. 3. When the vapour is at a temperature greater than the impregnation temperature. it is said to be as superheated vapour. 4. At the critical point. the concentrated liquid and saturated vapour province are indistinguishable. 5. At supercritical force per unit areas. the substance is merely termed fluid instead than liquid or vapour. 6. If the initial force per unit area at –200C is 0. 260 kPa. heat transportation consequences in addition of temperature to –100C. Ice passes straight from the solid stage to vapor stage. 7. At the ternary point ( 0. 6113 kPa ) and a temperature of –200C. allow heat reassign increase the temperature until it reaches 0. 010C. At this point. farther heat transportation may do some ice to go vapour and some to go liquid. The three stages may be present at the same time in equilibrium.
Tables of Thermodynamic Properties
Tables of thermodynamic belongingss of many substances are available. and in general. all these have same signifier.
Steam tabular arraies are selected because steam is used extensively in power workss and industrial procedures. The steam tabular arraies provide the information of utile thermodynamic belongingss like T. P. v. u. H and s for concentrated liquid. saturated vapour and superheated vapour.
Since the belongingss like internal energy. heat content and information of a system can non be straight measured ; they are related to alter in the energy of the system. Hence one can find ?u. ?h. ?s. but non the absolute values of these belongingss. Therefore it is necessary to take a mention province to which these belongingss are randomly assigned some numerical values.
For H2O. the ternary point ( T = 0. 01o C and P = 0. 6113 kPa ) is selected as the mention province. where the internal energy and information of saturated liquid are assigned a zero value. In the concentrated steam tabular arraies. the belongingss of concentrated liquid that is in equilibrium with concentrated vapours are presented.
During phase passage. the force per unit area and temperature are non independent of each other. If the temperature is specified. the force per unit area at which both stages coexist in equilibrium is equal to the impregnation force per unit area.
Therefore. it is possible to take either temperature or force per unit area as the independent variable. to stipulate the province of two-phase system.
Depending on whether the temperature or force per unit area is used as the independent variable. the tabular arraies are called temperature or force per unit area tabular arraies.
The two phases- liquid and vapour can coexist in a province of equilibrium merely up to the critical point.
Therefore the listing of the thermodynamic belongingss of steam in the concentrated steam tabular arraies ends at the critical point ( 374. 15o C and 212. 2 saloon ) .
If the steam exists in merely one stage ( superheated steam ) . it is necessary to stipulate two independent variables. force per unit area and temperature. for the complete specification of the province. In the superheated steam tabular arraies. the properties- v. u. h. and s- are tabulated from the impregnation temperature to some temperature for a given force per unit area.
The thermodynamic belongingss of a liquid and vapor mixture can be evaluated in footings of its quality. In peculiar. the specific volume. specific internal energy. specific heat content and specific information of a mixture of quality X are given by
V = ( 1-X ) vf + Xvg. u = ( 1-X ) uf + Xug. H = ( 1-X ) hafnium + Xhg = hafnium + Xhfg. s = ( 1-X ) sf + Xhg where hfg = mercury – hafnium = latent chapeau of vaporisation.
The venue of all the saturated provinces gives the concentrated liquid curve AC and the venue of all the saturated vapour provinces gives the concentrated vapour provinces gives the concentrated vapour provinces gives the concentrated vapour curve BC.
The point C represents the critical point. The difference between vg and vf reduces as the force per unit area is increased. and at the critical point vg = vf.
At the critical point. the two phases-liquid and vapor- are identical.
The pressure-volume ( P-V ) diagram for a pure substance is shown in Figure. The curves AC and BC represent the concentrated liquid curve and saturated vapours curve. severally. and C is critical point.
The country under the curve represents the two-phase part. Any point M in this part is a mixture of saturated liquid ( shown as degree Fahrenheit ) and saturated vapour ( g ) .
Mollier ( h-s ) Diagram
The h-s diagram was introduced by Richard Mollier and was named after him. It consists of a household of changeless force per unit area lines. changeless temperature lines and changeless volume lines plotted on enthalpy versus information co-ordinates. In the two-phase part. the changeless force per unit area and changeless temperature lines coincide.